[Partial physeal growth arrest with increasing genu varum deformity caused by a cortical enchondroma--a case report].

INTRODUCTION: Trauma or infectious diseases can cause destruction of the epiphyseal region of the knee with premature partial bridging of the physis and deviation of length and axis. There is only little information about tumorous lesions as pathogenetic factor for these deviations. We have been searching for an approach to take advantage of the particular growth potential in order to avoid further complex procedures.
METHOD: We report the case of a 6-year-old girl with progredient varus deformity of the left knee and reduction of walking distance. The X-ray and MRI investigations have shown a benign lesion like osteofibroma of the mediodistal femur with an affection of the medial physis. Because of the early and rapidly progredient deformity we planned an operative intervention, including the following two steps: 1) resection of the benign lesion and arthroscopically assisted resection of the bony bar with fat-patch interposition; 2) lateral hemiepiphyseodesis with an eight-plate. The histological examination revealed a cortical enchondroma, which had caused the above-mentioned growth disturbance. During follow-up (clinical and radiological examinations every 3 months) we saw a nearly normal growth of the mediodistal femoral physis with consecutive correction of the axial deviation.
RESULTS: With surgical intervention (resection and temporary lateral hemiepiphyseodesis) we achieved a complete deformity correction in reference to the opposite side within one year post operation. Removal of the eight-plate has already been accomplished. Follow-up will be continued until completion of growth.
CONCLUSION: In cases of rare partial bridging of the physis induced by a benign bone tumour one can achieve early correction of axial deviation during growth with resection, interposition of a fat patch and temporary hemiepiphyseodesis. With the help of such a procedure it is possible to prevent further progression of a pre-existing deformity and later aggressive surgical intervention.